1. Field of the Invention
This invention relates to a method for positioning glass sheets for forming.
2. Background Art
Glass sheets are conventionally formed by heating on a conveyor within a furnace and then forming prior to delivery for cooling. Such cooling can be slow cooling to provide annealing or faster cooling that provides heat strengthening or tempering. In connection with heating of the glass sheets, see U.S. Pat. Nos. 3,806,312 McMaster et al.; 3,947,242 McMaster et al.; 3,994,711 McMaster; 4,404,011 McMaster; and 4,512,460 McMaster. In connection with glass sheet forming, see U.S. Pat. Nos. 4,204,854 McMaster et al.; 4,222,763 McMaster; 4,282,026 McMaster et al.; 4,437,871 McMaster et al.; 4,575,390 McMaster; 4,661,141 Nitschke et al.; 4,662,925 Thimons et al.; 5,004,491 McMaster et al.; 5,330,550 Kuster et al.; 5,376,158 Shetterly et al.; 5,472,470 Kormanyos et al.; 5,900,034 Mumford et al.; 5,906,668 Mumford et al.; 5,925,162 Nitschke et al.; 6,032,491 Nitschke et al.; 6,173,587 Mumford et al.; 6,227,008 Shetterly; 6,418,754 Nitschke et al.; 6,543,255 Bennett et al.; 6,578,383 Bennett et al.; 6,718,798 Nitschke et al.; 6,729,160 Nitschke et al. In connection with the cooling, see U.S. Pat. Nos. 3,936,291 McMaster; 4,470,838 McMaster et al.; 4,525,193 McMaster et al.; 4,946,491 Barr; 5,385,786 Shetterly et al.; 5,917,107 Ducat et al.; 6,079,094 Ducat et al.; and 6,513,348 Bennett et al.
Vehicle windshields are conventionally manufactured from outer and inner formed glass sheets and an intermediate layer of polyvinyl butyral. The outer and inner glass sheets have different sizes since the outwardly curved shape of the formed windshield necessitates that the outer glass sheet be slightly greater in size than the inner glass sheet. Also, upon manufacturing, there can be slight variations in the size of flat glass prior to the forming. Thus, switches which have previously been utilized to sense the approach of a glass sheet to initiate transfer from a conveyor for forming do not necessarily initiate transfer that positions the glass centrally on a forming mold for the forming.